C#.NET — Defaults, variable-argument methods, and error types in definitions. Which statements are correct? C# allows a function to have arguments with default values. C# allows a function to have a variable number of arguments. Omitting the return value type in a method definition results in an exception. Redefining a method parameter inside the method body causes an exception. The params keyword specifies a variable number of arguments.

Introduction / Context:
This question mixes method defaults, variable argument lists, and the distinction between compile-time errors and runtime exceptions in C# method declarations and bodies.

Given Data / Assumptions:

• Five statements discuss defaults, params, and error types.
• We must identify which combination is correct.

Concept / Approach:
In C#, default parameter values are supported. Variable-length argument lists are supported using the params keyword (and such an argument must be last). Omitting a return type or attempting to redeclare a parameter name inside the method does not cause a runtime exception; instead, these are compile-time errors. Therefore, statements 1, 2, and 5 are accurate, while 3 and 4 are inaccurate as phrased (they misuse “exception”). No option lists exactly 1, 2, and 5 together, so “None of these” is the only correct choice.

Step-by-Step Solution:

Verification / Alternative check:
Attempt to compile samples: removing a return type fails at compile time; re-declaring a local that conflicts with a parameter name fails likewise; defaults and params compile and behave as expected.

Why Other Options Are Wrong:

• A includes 3 (false).
• B includes 3 and 4 (both false).
• C includes 2 and 5 but omits 1 (true).
• D includes 4 (false).

Common Pitfalls:
Mixing up exceptions (runtime) with compiler diagnostics; forgetting that params must be the last parameter.

Final Answer:
None of these